CHAPTKR XI-VI I.
COMPARATIVE FUSIBILITY OF FOUNDRY METALS.*
In the advance of founding to a basis of ^reater exactness and assurance of successful workings, it. is «>ftcn as essential for us to have information on the fusibility of the metals we make mixtures from, as to know the effeet of one metalloid upon another in ehan^'in^' the physical character of iron. This is real-i/ed when we consider how easily a formulated mixture can be prevented from Kiv'n,% calculated results, by <me metal having a lower fusing point than another \vhen charged into a cupola. While this is a subject of importance to the general and heavy-work founder, who is often called upon to lake several different grades out of a cupola, at. one l* heat/" it is also <»f importance to the specially and b'^ht'-work founder who may be char^in^' irons of different grades to make one or two mixtures for a whole heal, for when the latter knows that one combination of certain metalloids requires greater heat than others he is in a much better posit ion to decide whether it is the. iron, blast, atmosphere, fuel, mischance, or his own mismanage-
"This chapter comprises two puprrs, rrvisrcl for this work, which Ihr author prrst'iitffi tvspcclivrly to the PiUMbur# K<nm» <!ryin«tn's Assorialioii in Jniu\ i^»;7, ami to the \Wr4t*ni I''otintlry-
iiu-n's Assnrsutioii at dncintiati, in Odnln-r of UK* *,amt« year.studying the cause.s; and ('onnells-villecoke for fuel, of which .v»uo pounds were use<l for the bed ami .150 pounds between charges. The pi*.»- on bed was S,ooo pounds and between cliaj'^'es 6,000 pounds. We used limestone for a, ilux; for every three tons we used about 90 pounds, placed on top of ever}1 charge. There is no doubt that one or two hundredweight. <»f slai.^ could be added to the totals iMven above, whi«'h eouM be ;«;ather«Ml from the. skim-mini;-of ihf ladh- and tin- droppint-, of the bottoms. Our «Mj)pnrheii.sion as to loss of iron through slai;" was r> ">'•• I I O/..